A curdmaking process is used to transform cheese milk into quality cheese curd with the highest possible yield. In use, this cheese vat is filled with cheese milk (optionally pre-acidified), and then caused to coagulate by addition of enzyme and acid, acid alone, or a composite coagulant to the cheese milk. Various types of cheese have respective production procedures. Once the cheese milk has coagulated to form a curd, it is important to handle the curd gently as it is still soft. A portion of whey is drained. As the whey is removed, the cheese mass turns harder. After whey is removed, the curd and remaining whey are then transferred for subsequent processing, such as processing over a slotted conveyor or such to further drain whey from the curd.
One issue in separating the curd and whey is that small curd particles that often leave the vat together with drained whey. This loss of curd can significantly reduce yield, and processing techniques have been developed which seek to reclaim these curd particles from the whey stream and reincorporate them into the cheese mass. Reductions in yield resulting from these curd particles can be reduced or avoided by continuously stirring the curd and whey while draining the whey. However, simple strainers, such as meshes, quickly become clogged with curd particles. U.S. Pat. No. 6,050,179, herein incorporated by reference in its entirety, describes a strainer disc device for draining whey while stirring the curd and whey. The disclosed strainer has a circularly shaped strainer disc rotatably arranged flat against a wall of a cheese vat. It is intended that the rotation of the strainer disc is sufficient to prevent the accumulation of curd particles and associated clogging of the strainer disc. Additionally, rotation of the agitator during stirring is also intended to help remove any curd particles which manage to adhere to the strainer disc by performing mechanical scraping of the strainer disc.
However, the inventors have recognized a number of issues with this strainer disc. First, the curd is extremely fragile in the beginning of the cheese-making process. Shear stress created by the rotating strainer disc damages the curd and crease small curd particles which escape through the strainer disc with the whey, which reduces yield. Second, limitations to the size of the disc limit the capacity of the strainer. Third, there are inconsistent flow characteristics on the surface of the strainer disc, which make it difficult to determine and maintain optimal settings for its operation from batch to batch or unit to unit.